Abstract
Purpose::
Timely and accurate diagnosis of fungal keratitis remains a problem. The potential utility of polymerase chain reaction based techniques for addressing these issues is well recognized. Here, we test the applicability of bead array technology for the rapid identification of ocular pathogens, specifically of the genera Candida, in infected corneal tissue.
Methods::
Various strains of C. albicans were isolated from patients with Candida keratitis. The strains were identified at BPEI using standard mycologic methods, such as germ tube and direct microscopic examination. DNA was extracted from these pure cultures. Species specific probes were designed with different computer programs and public databases and validated with a captured probe hybridization format. The strains were identified using the xMAP detection system, a suspension bead assay. Following assay validation, corneal scrapings from humans were inoculated with an aliquot of C. albicans pure culture. Twenty four hours after inoculation, the samples were extracted, amplified, and identified using th xMAP suspension bead assay.
Results::
The identity of the strains as determined by the xMAP suspension bead assay correlated 100% with the conventional mycologic identification techniques used at Bascom Palmer Eye Institute.
Conclusions::
The data indicate the xMAP suspension bead assay offers a reliable means of identifying different strains of C. albicans when compared to standard mycological identification techniques. Furthermore, the DNA extraction method, PCR and hybridization conditions are adequate and therefore provide a good platform for further assay development. The data supports the hypothesis that the xMAP suspension bead assay can be employed as a rapid non-culture based detection and identification method for common fungal pathogens, including Candida, Aspergillus, and Fusarium.
Keywords: fungal disease • cornea: clinical science • clinical laboratory testing